Pituitary Gland
The pituitary gland is a small gland just below the hypothalamus. It is divided into two parts the anterior and posterior pituitary. Both are connected to and influenced by the hypothalamus. It is responsible for the creation and secretion of several different hormones that control a variety of bodily functions. Anterior Pituitary The anterior pituitary is the largest part of the pituitary gland and secretes several different hormones. There are four hormones that are collectively referred to as tropic hormones. TSH stimulates the thyroid gland to produce T3 and T4. Adrenocorticotropic hormone (ACTH) controls the release of corticosteroids from the adrenal cortex. Follicle stimulating hormone (FSH) regulates estrogen production and the developement of sperm and ova. Leutenizing hormone (LH) is responsible for ovulation and estrogen in women and testosterone production in men. Together FSH and LH are referred to as gonadotropic hormones. Growth hormone is responsible for bone and muscle growth as well as metabolism of the macronutrients (protein, fat, carbohydrates). Prolactin initiates breast tissue growth and lactation after childbirth. The simple list: TSH, ACTH, FSH, LH, GH, Prolactin. Posterior Pituitary The posterior pituitary does not manufacture any hormones of its own but merely secretes two hormones produced in the hypothalamus. Oxytocin influences lactation and is responsible for uterine contractions during labor. Antidiuretic hormone controls whether or not the kidney's retain or release water. The more ADH in circulation the more H2O is retained by the kidneys. This is done to control blood pressure by manipulating fluid volume and fight dehydration. Factors that stimulate ADH release and increse fluid volume and water retention are decreased fluid volume, increased plasm osmolality, hypotension, pain, nausea and vomiting. Factors that inhibit and can lead to excess fluid loss are alcohol, beta agonist (increase P and B/P, used to treat bradycardia, COPD, asthma amongst others), and decreased plasma osmolality. A note on osmolality: The text here is confusing but it is important to have an understanding of what it is. Osmolality, specifically plasma osmolality, merely refers to how concentrated blood is. The higher the osmolality the lower the fluid volume and higher the solute count in blood. High plasma osmolality is synonymous with dehydration and low plasma osmolality is synonomous with overhydration. Medical Conditions Given the number of hormones released from the pituitary a malfunction here can affect any of the body systems. Causes can be tumor, infection, trauma or surgery. Below is a partial list of hormone imbalances and the medical conditions associated with them. These are just the ones covered in lecture and text as being relevant. *TSH - Hyper and Hypo thyroidism *ACTH - Addison's and Cushing's *GH - Acromegaly and dwarfism (neither is likely to be on the test) *ADH - Diabetes Insipidis and Syndrome of Inappropriate Antidiuretic Hormone (SAIDH). Treatment Surgical removal of the pituitary is possible but requires massive medical treatment and drug therapy for life. It is preferrable to treat just the specific systems affected unless a patients life is at stake. See specific conditions under the endocrine category for treatment of specific disorders. Category:241 Test 1 Category:Endocrine